Abstract
Analysis of voice pathologies may require vocal fold models that include relevant features such as vocal fold asymmetric collision. The present study numerically addresses the problem of frictionless asymmetric collision in a self-sustained three-dimensional continuum model of the vocal folds. Theoretical background and numerical analysis of the finite-element position-based contact model are presented, along with validation. A novel contact detection mechanism capable to detect collision in asymmetric oscillations is developed. The effect of inexact contact constraint enforcement on vocal fold dynamics is examined by different variational methods for inequality constrained minimization problems, namely the Lagrange multiplier method and the penalty method. In contrast to the penalty solution, which is related to classical spring-like contact forces, numerical examples show that the parameter-independent Lagrange multiplier solution is more robust and accurate in the estimation of dynamical and mechanical features at vocal fold contact. Furthermore, special attention is paid to the temporal integration schemes in relation to the contact problem, the results suggesting an advantage of highly diffusive schemes. Finally, vocal fold contact enforcement is shown to affect asymmetric oscillations. The present model may be adapted to existing vocal fold models, which may contribute to a better understanding of the effect of the non-linear contact phenomenon on phonation.

Abstract
Continuous and prolonged use of the speaking voice may lead to functional speech disorders that are not apparent for voice clinicians from high-speed imaging of the vocal folds’ vibration. However, it is hypothesized that time dependent tissue properties provide some insight into the injury process. To infer material parameters via an inverse optimization problem from recorded deformation, a self sustained theoretical model of the vocal folds is needed. With this purpose, a transversely isotropic three-dimensional nite element model is proposed and investigated. Special attention is paid to the collision and time integration schemes. Accuracy in the deformation process is introduced by means of a topology-adaptive method for deformable interface tracking, called the Deformable Simplicial Complex, which has been previously applied to immiscible uids. For computational reasons, aerodynamic driving forces are derived from Bernoulli’s principle.

Abstract
The ACM SIGGRAPH / Eurographics Symposium on Computer Animation (SCA) is the premier forum for innovations in the software and technology of computer animation. The 13rd annual event unites researchers and practitioners working on all aspects of time-based phenomena. Our focused, intimate gathering, with single track program and emphasis on community interaction, makes SCA the best venue to exchange research results, get inspired, and set up collaborations. We invite submission of original, high-quality work in the form of technical papers and posters. All details can be found in the For Submitters section.